How to add DNS filtering to your NAT instance with Squid Sept. 5, 2019, 11:36 a.m.

In this post, I discuss and give an example of how to use Squid, a leading open-source proxy, to implement a “transparent proxy” that can restrict both HTTP and HTTPS outbound traffic to a given set of Internet domains, while being fully transparent for instances in the private subnet.

tutorial aws networking squid

Creating Custom Secure LDAP Certificates for Domain Controllers with Auto Renewal Sept. 4, 2019, 12:15 p.m.

The primary reason for enabling this functionality is to allow third-party applications that aren’t capable of performing secure binds or encrypted LDAP sessions (over TCP 389) to connect securely.

active directory security windows

Identifying Clear Text LDAP binds to your DC’s Sept. 4, 2019, 12:15 p.m.

The core of the issue is this, when an application performs a simple LDAP bind, the username and password is transmitted in clear text in the very first packet. The DC doesn't even have a chance to prevent this exposure from occurring.  If this connection is not encrypted at a lower layer such as TLS or IPSec, it may be intercepted and a bad day may soon follow.

active directory security windows ldap

Automatic Updates Aug. 29, 2019, 5:23 p.m.

The unattended-upgrades package can be used to automatically install updated packages, and can be configured to update all packages or just install security updates. To configure unattended-upgrades, edit /etc/apt/apt.conf.d/50unattended-upgrades. To enable automatic updates, edit /etc/apt/apt.conf.d/20auto-upgrades.

documentation sysadmin ubuntu

Logging Cheat-Sheets Aug. 29, 2019, 5:21 p.m.

In looking into compromised systems, often what is needed by incident responders and investigators is not enabled or configured when it comes to logging.  To help get system logs properly Enabled and Configured, below are some cheat sheets to help you do logging well and so the needed data we all need is there when we look.

documentation sysadmin tips

Windows Time Service Tools and Settings Aug. 29, 2019, 5:20 p.m.

Tools and settings for the windows time service.

windows

UniFi Controller API Aug. 16, 2019, 9:23 p.m.

Documentation of API endpoints on the UniFi controller software. This is a reverse engineering project that is based on browser captures, jar dumps, and reviewing other software that has been written to work with the controller. It's received minimal testing.

ubiquiti documentation api

Why does each drive have its own current directory? July 16, 2019, 3:41 p.m.

Remembering the current directory for each drive has been preserved ever since DOS 1.0, although there isn’t actually such a concept as a per-drive current directory in Win32. The appearance that each drive has its own current directory is a fake-out by cmd.exe which uses environment variables to create the illusion to batch files that each drive has its own current directory.

windows

Installing and Configuring OpenSSH on Windows Server 2019 June 11, 2019, 12:16 p.m.

Windows Server 2019 and the most recent version of Windows 10 include the ability to install both an SSH client and an SSH server. To get an SSH client onto Windows 10 or Windows Server 2019, without using 3rd party software or installing Windows Subsystem for Linux, use the PowerShell command:

Add-WindowsCapability -Online -Name OpenSSH.Client~~~~0.0.1.0
windows windows server 2019 ssh

AWS Systems Manager Automation June 7, 2019, 9:25 a.m.

Systems Manager Automation simplifies common maintenance and deployment tasks of Amazon EC2 instances and other AWS resources. Automation enables you to do the following.

  • Build Automation workflows to configure and manage instances and AWS resources.
  • Create custom workflows or use pre-defined workflows maintained by AWS.
  • Receive notifications about Automation tasks and workflows by using Amazon CloudWatch Events.
  • Monitor Automation progress and execution details by using the Amazon EC2 or the AWS Systems Manager console.
automation aws

PSWindowsUpdate June 7, 2019, 9:24 a.m.

This is a fork of Michal Gajda's PSWindowsUpdate PowerShell module. The original module can be found on the PowerShell Gallery.

windows github powershell

Windows Update Agent API June 7, 2019, 9:23 a.m.

The Windows Update Agent (WUA) API is a set of COM interfaces that enable system administrators and programmers to access Windows Update and Windows Server Update Services (WSUS). Scripts and programs can be written to examine which updates are currently available for a computer, and then you can install or uninstall updates.

windows scripting

How to access both subnets (dual NIC) on Ubuntu server from third subnet? May 8, 2019, 10:31 a.m.

If the router is filtering too, ubuntu has to be aware of the gateway's existence for both interfaces and use table and rule settings for a correct routing.

linux networking homelab

Two Default Gateways on One System May 8, 2019, 10:29 a.m.

Normally, a Linux system only has one routing table, in which only one default gateway can make entries. With iproute2, you have the ability to setup an additional routing table, for one thing, and allow this table to be used by the system based on rules, for another.

linux networking homelab

Ubiquiti EdgeRouter Lite SOHO Network Design April 20, 2019, 9:06 p.m.

This project describes the Ubiquiti EdgeRouter Lite (and EdgeRouter 4), EdgeSwitch 24 and UniFi Access Point network design for a SOHO (Small Office/Home Office) network.

ubiquiti networking

A Treatise on Group Policy Troubleshooting–now with GPSVC Log Analysis! April 10, 2019, 3:09 p.m.

This guide outlines basic steps used to troubleshoot Group Policy application errors using the Group Policy Service Debug logs (gpsvc.log).

Enable by setting HKLM\Software\Microsoft\Windows NT\CurrentVersion\Diagnostics\GPSvcDebugLevel REG_DWORD to 30002 (hex), and ensure %windir%\debug\usermode exists. The gpsvc.log log will be created in this directory when updating group policy (eg gpupdate /force).

windows troubleshooting group policy

How Healthy is your LAPS Environment? April 6, 2019, 3:41 p.m.

LAPS is easy to deploy and works great. The challenge comes in knowing if it’s actually working. How do you know if your machines have ever set the password? Or maybe they set it once and haven’t updated it since even though it’s past the designated expiration date? It’s definitely worth monitoring to ensure that your machines are operating as expected. Jiri Formacek (the creator of LAPS), threw together a small PowerShell script to provide that capability.

windows active directory security

Newbie at bash scripting? Here's some advice. April 5, 2019, 11:43 a.m.

Bash is powerful, it is super permissive, and because of that, it is extremely easy to do something stupid with it. This blogpost is more about good conventions in bash, not it's syntax or how to do basic stuff with it.

bash shell

How to do things safely in bash April 5, 2019, 11:42 a.m.

Like programming in C or driving a car, contemporary shellscript languages require some knowledge and discipline to use safely, but that's not to say it can't be done. This guide is here to show that in bash, it can be done. Specifically, those systematic bugs that the language encourages can be eliminated by disciplines that are outlined here. Realize that Bash is not a language where the correct way to do something is also the easiest.

bash shell

The Bash Hackers Wiki April 5, 2019, 11:41 a.m.

This wiki is intended to provide human-readable documentation and information so users aren't forced to read every bit of the Bash manpage - which can be difficult to understand.

bash shell